The detection and quantification of gas, especially the flammable and poisonous gases in air are extremely important due to their great demands in areas such as environmental monitoring, coal mine safety, industrial production, and automobile exhaust monitoring, etc. A number of methods have been used to detect gas species including spectroscopy, electrochemistry, and photoacoustics, each having various disadvantages. Multiple gases often co-exist in complicated environments, further complicating design successful of detection devices. For example, the gas in coal mines may compose methane (CH4), ammonia (NH3), carbon monoxide (CO), sulfur dioxide (SO2), hydrogen sulfide (H2S), etc. CH4 is unavoidable to be released during the coal mining and it outbursts in both underground and surface mines, but must be tracked and monitored. When CH4 reaches a concentration of 5-15% in air in a closed environment, CH4 becomes dangerously explosive. Similarly, C2H2 and NH3 are released during industrial production and they are extremely explosive gases when their concentrations reach 2.5%-80% and 16-25%, respectively. Therefore, multiplex gas detection is quite necessary, and usually several wavelengths are required for the simultaneous multiplex gas detection using spectroscopy method. Traditional instrument's light sources usually generate single wavelength light, and their physical size is bulky, their optical stability and specificity are low. Additionally, simultaneous detection and measurement of multiple gases is difficult.